When is ARAM getting Champion Mastery?

I was hoping someone could tell me when ARAM is getting champion mastery. IIRC, Riot promised that ARAM would eventually be included, and its been awhile without any updates. This is especially frustrating because they've been able to add Mastery to the Rotating Game Mode, but have still neglected ARAM. If anyone could provide any info it would be much appreciated, thanks!